Hardware User Guide
3-6 Xilinx Development System
is ground. The power supply should provide at least 250 mA of
current to drive the LED displays.
Unregulated Power Input (J12)
This input provides a way to power the FPGA Demonstration Board
from an unregulated source, such as a 9 V battery or an AC adapter.
Typically, the input should be 7VDC - 12VDC at 250 mA. You must
consider the power dissipation requirements of the U3 voltage regu-
lator if the voltage input is greater than 9 V.
The J12 unregulated power input provides two holes to connect the
unregulated power source. The hole with the square pad, marked
with a "+" is the positive input. The other hole, marked with a "-" is
circuit ground. The positive input is connected through the power
on-off switch SW2–1 to U3–1, which is the optional +5 V regulator. U3
must be installed to use this input.
+5 V Regulator Option (U3)
You can install a three terminal +5 V regulator, such as the LM2940CT
shown in the following figure. This regulator powers the demonstra-
tion board from an unregulated power supply, such as a +9 V battery.
Pin 1 (square pad) is Vin, pin 2 is ground, and pin 3 is +5 V out.
Note Insulate the metal heat sink tab of the regulator from traces and
vias on the PCB.
Figure 3-3 LM2940CT +5 V Regulator
X4692
Pin1
LM2940CT
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